Why should we brush our teeth before going to bed?

[ebisimark0013]

Our mouths are full of bacteria. Hundreds of different types live on our teeth, gums, tongue and other places in our mouths. Some bacteria are helpful. But some can be harmful such as those that play a role in the tooth decay process. Tooth decay is the result of an infection with certain types of bacteria that use sugars in food to make acids. Over time, these acids can make a cavity in the tooth.

http://www.youtube.com/watch?v=vT-DcI5czIQ